Sheet-metal work.



0. P. SHEPHERD & E. S. CONRAD.

SHEET METAL WORK. APPLIGATION FILED JAN. 14, 1911.

Patented Feb. 6, 1912.

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CHARLES P. SHEPHERD AND EDWIN S. CONRAD, OF GRAND RAPIDS, MICHIGAN.

4 SHEET-METAL WORK.

Patented Feb. 6, 1912.

- Application led January 14, 1911. Serial No. 602,735.

To all whom t may concern:

Be it known vthat we, CHARLES P. SHEP- HEED and EDWIN S. CONRAD, citizens of the United States of America, residing at Grand Rapids, in the county of Kent and State of Michigan, 'have invented certain new and useful Improvements in Sheet-Metal Work; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in'the art to which it appertains -to make side ofthe wedge anda bifurcated projectionon theopposite edge formed with its outer sides substantially parallel and its ends convex, the respective shape of the recesses and projections being the same, so that when the projections are forced endwise into the svaid recess and spread apart by the wedge portion the projections completely fill the recesses, thus making a tight joint whereby the edges are locked to each other by a substantially dovetail connection as will 4more fully appear by reference to ing drawings in which:

Figure 1 represents a portion of a tube embodying our invention; Fig. 2 the same partially formed up; and Fig. 3 the same with the projections partially insertedywithin the recess. i i" the figures.

the accompany- Like numbers refer 1 represents. the body of Va sheet metal tube having a longitudinal seam as at 2.

In one edgel of the sheet forming'the tube, at convenient intervals, are formed 'recesses 3 having inwardly diverging opposite walls forming a substantially dovetail recess. At the. bottom of each recess isA a wedge shaped projection 4 having oppositely inclined -sidesfwhereby there are formed al pair of diverging recesses. On the opposite edge of the sheet forming the tube and opposite each pair of recesses is a bifurca-ted projection 5 having parallel outer sides andadapted 4when spread apart by the wedge 4 to fit closely within the \recesses 3 3.' This spreading action is accomplished whenever to like parts in all of the edges of the metal are forced in close i.

contact and the projebtions forced endwise-- into the recesses.

What we claim 1s A sheet metal tube having a longitudinalS seam and provided with arecess in one edge having diverging opposite walls, a wedge projecting into the recess, said recess having concave bottom portionsat the respective sides of the Wedge, and projections on the other edge having convex ends of the same 'curvature as the concave portions of the recesses and adaptedto completely fill the recesses, when forced into the same and spread apart by the wedge.V

In testimony whereof we atx our signatures in presence of twowitnesses.

M CHARLES P. sHEPHEED. v EDWIN S. CONRAD. Witnesses:

PALMER A. JONES, LUTHER V. MoUL'roN. 

